FAQ02075 of Solid-state Relays FAQ

What should be done about surge-absorbing circuits for AC-load Solid-state Relays?

Answer

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Measures against AC Switching Solid-state Relay Output Noise Surges

1.The Solid-state Relay has a built-in snubber circuit to smooth out a sudden rise in voltage. If there is a large voltage surge in the output-side AC power supply, the snubber circuit will not be sufficient to suppress the surge, and overvoltage will damage the output elements.

3.Be sure to take measures against surge when switching an inductive load with an Solid-state Relay that does not have a built-in surge-absorbing element. (Refer to the following figure.)

Note:A separate varistor with a surge resistance higher than the built-in varistor must be mounted externally if influence is possible from noise that is not completely absorbed by the built-in varistor (surge resistance: 700 to 1000 A).

Select a surge-absorbing element that meets the conditions in the following table.